A U.S. lawyer entered a not guilty plea Wednesday on behalf of a company controlled by Yevgeny Prigozhin, a Russian caterer nicknamed Putin’s chef, to charges accusing it of interfering in the 2016 elections.

The business, Concord Management and Consulting LLC, was the first of three companies and 13 Russian nationals to respond to the charges by Special Counsel Robert Mueller. A February indictment accuses them of producing propaganda, posing as U.S. activists and posting political content on social media as so-called trolls to encourage strife in the U.S.

U.S. Magistrate Judge G. Michael Harvey accepted the not guilty plea on behalf of the company from Eric Dubelier, a lawyer at Reed Smith LLP. Concord is one of two companies controlled by Prigozhin, who is also charged in an indictment that accuses them of engaging in operations to interfere with the elections and the political process.

Dubelier and prosecutors sparred in court filings in recent days. Dubelier posed a series of pointed questions about how prosecutors built their case and the identity of all witnesses and cooperators.

Prosecutors told the judge that Dubelier had refused to confirm whether Concord has been served with a summons. They said that without such confirmation, there was no guarantee that Concord would accept the court’s jurisdiction and abide by the federal rules of procedure. But a judge refused the request by prosecutors to postpone the arraignment.

Previous attempts to get the Russian government to help deliver the summons to Saint Petersburg-based Concord Management have failed, prosecutors said, adding that they want Dubelier to inform the court by May 25 whether Concord was served.

The 37-page indictment describes how hundreds of Russians used social media, fake rallies and secretive operatives in the U.S. to create “political intensity” among radical groups, opposition social movements and disaffected voters. In 2014, the indictment says, several Russians traveled to the U.S. under false pretenses “to collect intelligence for their interference operations.”

Prigozhin is known as Putin’s chef because of his close ties to President Vladimir Putin — Concord Management provides food services to the Kremlin. Mueller also accuses a related catering firm and another Prigozhin group called the Internet Research Agency with running a vast troll operation designed to sow discord in the 2016 U.S. presidential election. Prigozhin has known Putin since the 1990s, when both lived in Saint Petersburg and Putin was the city’s deputy mayor.